This invention relates generally to a housing for enclosure of a metal chassis and more specifically towards a means for securing a plastic bezel housing onto a metal chassis.
Conventionally an electronic appliance, such as a server or personal computer, is mounted in a metal chassis that is encased in an outer housing or bezel. The outer housing or bezel is used as a cosmetic and functional cover for the protection of PC boards mounted inside the metal chassis. The outer housing or bezel is typically made of plastic and is typically attached to the metal chassis housing using an attachment means that extends into the fire enclosure of the metal chassis.
Traditionally, plastic snaps are used to secure the plastic bezel to the metal chassis. The plastic snaps which extend from the main body of the bezel are formed integral to the plastic bezel using an injection molding process. The plastic snaps include an elongate generally cylindrical structure that is terminated by a foot structure. The foot structure has a width that is larger than the width of the elongate structure from which it extends and is slightly larger than its corresponding opening the sheet metal chassis.
The plastic material of the bezel is chosen so that the plastic snaps have sufficient flexure to flex inward. To secure the bezel to the metal chassis, the technician presses inward on the elongate structure of the plastic snap so that the foot of the plastic snap fits inside its corresponding opening in the metal chassis. When the foot is positioned inside of the metal chassis opening, the inward pressure is removed and the foot of the snap is secured so that the plastic snap cannot be easily removed without the application of an inward pressure. Because the foot of the plastic snap extends into the fire enclosure of the metal chassis, the plastic material used for the bezel is required to have a high UL rating. Because the plastic snap is integral to the bezel, the entire plastic bezel must be made of the high UL rated material, increasing the bezel cost.
In a second bezel attachment configuration, the plastic snap previously described is replaced with an alternative bezel attachment mechanism. FIGS. 1A and 1B, show a prior art attachment mechanism comprised of a metal ball stud component 110 and a metal snap receptor component 112, where the opening in the metal snap receptor component is aligned with an opening in the metal chassis. The metal ball stud is a machined part that is comprised of a machined ball structure at a first end of the metal ball stud, a generally cylindrical elongate structure, and a threaded region. The threaded region is screwed into the plastic bezel so that it firmly attached to the plastic bezel.
The metal snap receptor component is a spring loaded clasping mechanism for receiving the ball structure of the metal ball stud. The opening of the metal snap receptor component is aligned to a corresponding opening formed in the metal chassis. The bezel is attached to the metal chassis by inserting the ball portion of the metal ball stud into the spring loaded clasping mechanism of the metal snap receptor component. Because only the metal stud component of the attachment mechanism extends into the fire enclosure of the metal chassis, the plastic bezel need not be comprised of a more expensive plastic material that has a high UL rating. The ability to use a cheaper plastic helps reduce the material costs of the bezel.
Although a cheaper plastic material may be used for the configuration shown in FIGS. 1A, and 1B, the metal ball stud configuration does require additional assembly compared to the plastic snap configuration since additional labor is required both to (1) screw in the snap receptor component onto the metal chassis and (2) to screw in the metal stud component into the plastic bezel. Further, the use of a screw as part of the bezel attachment mechanism, introduces the potential of the loss of a screw inside the metal chassis, increasing the possibility of a PC board short.
In an alternative bezel attachment configuration shown in FIG. 2, the bezel attachment mechanism is comprised of a plastic post 210 or boss formed integral to the plastic bezel and a metal snap 212. Preferably, the plastic post or boss includes a threaded interior portion that is formed using a conventional injection molding process. The metal snap component includes a plurality of bent metal fingers that circumscribe and extend from a circular opening for receiving a screw. The metal snap component is attached to the top surface of the plastic post using a screw. The bezel is attached to the metal chassis by inserting the metal snap component into a corresponding opening formed in the metal chassis.
Because only the metal snap component of the attachment mechanism extends into the fire enclosure of the metal chassis, there is no requirement that the plastic bezel be comprised of a comprised of a more expensive plastic material that has a high UL rating, thereby decreasing bezel material costs. However, the metal snap configuration shown in FIG. 2 does require additional required the use of a screw 214 to secure the metal snap component to the plastic bezel. The use of a screw as part of the bezel attachment mechanism, introduces the potential of the loss of a screw inside the metal chassis, increasing the possibility of a PC board short.
In a fourth bezel attachment configuration, the requirement of a screw to attach the metal component is eliminated. The bezel attachment mechanism is comprised of a plastic post or boss (not shown) formed integral and a metal snap component 310 that slides over the plastic post or boss. The metal snap component 310 includes an elongate generally cylindrical region 312 that slips over the post of the bezel and an attachment region 314 that includes a plurality of bent fingers that extends from the elongate region. The elongate region includes a plurality of inwardly punched triangular regions that are used to dig into the plastic boss, thus providing a more secure attachment. To attach the plastic bezel to the metal chassis, the attachment region of the metal snap component is inserted into a corresponding opening of the metal chassis.
Because the only portion of the bezel snap that fits into the metal chassis is the attachment region, a less expensive plastic that is not UL rated may be used for the plastic bezel. Further, assembly costs are low since the metal snap component does not have to be secured by screwing the component onto the post, but is merely slid over the plastic post of the bezel. Unfortunately, although assembly is easy because the metal snap component does not need to be screwed onto the plastic post, the attachment of the metal snap component may not be as secure as the configurations shown in FIGS. 1 and 2. After multiple removals, the metal snap component may slide off the bezel post and may need to be reattached. In addition, because the metal snap component may slide off into the metal chassis when being removed, the possibility of a PC board short is introduced.
An inexpensive method and apparatus for firmly securing a bezel to a metal chassis that is inexpensive and easy to assemble is needed.